hammer



{No Model.)

W. J. HAMMER.

SAFETY DEVICE FOR ELEGTRIG CIRCUITS.

No. 400.669. Patented Apr. 2, 1889.

N. PETERS, Phnkn Lllhogrnphcr. Washington. D. C.

UNITED STATES PATENT OEErcE.

IYIIIIIIAH J. HAMMER, UF BOSTON, MAIPIACIII RET'IS.

SAFETY DEVICE FOR ELECTRIC CIRCUITS.

SPECIFICATION forming part Of Letters Patent No. 400,669, dated April 2, 1889.

Application filed December 9, 1886. Serial No. 221,087. fNo model.)

To (1 whom it may concern.-

Be it known that 1, WILLIAM J. HAMMER, of Boston, in the county of Suffolk and State of Massachusetts, have invented a certain new and useful Improvement in Safety Devices for Electrical Circuits, of which the following is a specification.

In my application filed November-19,1886, Serial No. 219,368, I have set forth an arrangement of safety-catches for electrical circuits wherein the safetycatches are so arranged that when one safety-catch is destroyed another of greater capacity may be switched into its place in the circuit.

My present invention relates to an improvement on this; and it consists, mainly, in providing means for automatically substituting one safety-catch for another. I prefer to perform this operation by mechanical means, though it may be done wholly or in part electrically.

I have devised several different ways of carryin g my invention into effect, which are illustrated in the accompanying drmvings.

Figure 1 illustrates the mode of operation in which a weight is used. Fig. 2 shows the use of a spring. Fig. 3 illustrates the employment of a magnet, and Fig. 'i that of a solenoid, for the purpose of replacing the safety-catch.

Referring first to Fig. 1, 1 2 represent a portion of an electrical circuit, which normally includes asafety catch or strip of fusible metal, This safety-catch is secured to metal plates 1) I). From plate I) a conductor, 0, extends to conductor 1, which is a part of the circuit. Passing through or connected wit-h plate Z) is a metal arm or two arms, (I d. To (Z is connected circuitcomiuctor 1. At or near the end of (Z is a weight, 6. Immediately below the plate I) is a contact-plate,f, preferably a double plate, as shown, so that the plate I) is adapted to enter between its parts. From plate f a sz'tfcty-catch strip, (1 extends to a plate,f', from which a conductor, g, extends to conductor 2. \Vhen the safetycatch a is fused and destroyed by an excessive current on the line, the arm (I d is released and falls by gravity, assisted by the weight 6, so that plate 1) makes contact with f and closes cireuitfrom 1 to 2 throughsafetycatch (1, which is made of greater cmiducting capacity than a, so that it is able to convey the current. This difference of conductivity is illustrated in the drawings by making the strip a in each figure slightly wider than the strip a. It may, however,evidently be accomplished in other ways. In the form shown in Fig. 2 the automatic substitution of the safety-cateh is accomplished by the action of a spring, 7L, instead of by gravity. Such spring is attached to arm 11, and when the normal safety-catch a breaks the spring draws the arm up and closes circuit through safetycatch (0' instead. In both these forms it will be seen that the substitute safety-catch is held mechanically out of circuit, and is placed therein by automatic mechanical means.

In Fig. 3 two double contact-plates, 7. and 7e, are shown connected, respectively, through safety-catches a and u, with conductor 1. A pivoted arm, I, included in the circuit, rests normally in contact with. plate It, being held there by a magnet, in, whose coils are included in the circuit. \Yhcn the circuit is broken by the destruction of the safety-catch (l, the magnet ceases to attract the arm, and the spring n, attached to said arm, at once draws it up against the contact 7.", bringing safety-cat ch (4 into the circuit. A substantially similar construction is shown in Fig. l. The circuitis thrown into a coil, 0, and the arm I has a magnetic extension, p, which forms a movable core for said coil. The effect is the same as that of the magnet in Fig. 3. In these forms the substitute safety-catch is held out of circuit electrically and placed therein mechanically.

It will of course be understood that while the magnet or solenoid is of su ftieient strength to hold the armature or core down it is not strong enough to draw it down when it is removed by the spring outside of the immediate magnetic field.

\Vhat I claim isl. The combination,with an electriealctmduetor, of a safetywateh normally in the circuit thereof, a substitute safety catch of greater conducting capaeil \',:u1d means for automatically placing the latter in circuit upon thcbrcakingof the former,substant ially as set forth.

The ecmbination, with an electrical conswitched automatically intc circuit, substanductor on a safety-catch normally in the cirtially as set forth. IO cuit, a switching device suspended by said This specification signed and witnessedtlus safety-catch, and a substitute safety-catch 0t (it-l1 day of December, 1886.

5'g'rcater conducting capacity provided with WM. J. HAMMER.

suitable terminals situated beneath said XVit-nesses: switching device, whereby upon the breaking FRANK E. PERRY, of the normal safety-catch the substitute is \V. C. LMVTON. 

